Process for the treatment of the surfaces of articles of aluminum.



' normed UNITED srnrus rn'rnnr onerou ALBERT LANG, OE KABLSRUHE, GERMANY.

PROCESS FOR THE TREATMENT OF TIE-IE SURFACES 01? ARTICLES 01: ALUMINUM.

No Drawing.

- Specification of Letters. Latent.

, Applicationfiled February 6, 1907. Serial No. 35$,109.

Patented Nov. 4, 1913.

To all whom it may concern:

Be it known that I, ALBERT Lane, a subject of the Grand Duke oi. Baden, Germany, residing at Karlsruhe, in'Ba-den, Germany, have invented a certain new and useful Process for the Treatment of the Surfaces of Articles of Aluminum, of which the following is a specification,

The employment of aluminum for cooking vessels, cart-ridge cases and for many other useful articles has been found to possess many disadvanta es on account of the low melting point of t e metal and the fact that it is not hard enough for various purposes, while, however," the low specific gravity wouldhave been of great value, Again the formation on the metal or" a layer or coating of oxid for example which would not be easily attacked has been considered impracticable hitherto. on account of the weak aflinity of aluminum for acids and alkalies; consequently manufacturers have satisfied themselves with the use of a coating of lacquer or of carbon, or with the application to the aluminum of layers of other metals either as a covering or as intermediateinsertions, but these expedients were not satisfactory for various reasons. It has been prptposed to color the layers of carbon deposit on the aluminum surface with metallic coloring matters, but of course this coloring is only incorporated with the external covering layers, and is not therefore firmly applied to the metal.

According possible to form an oxidized coating or layer on'the aluminum, this la or having good fire-resisting pro erties whi e it is permanent and can if esired be colored or enameled; the layer of color does not rest loosely on the material but becomes permanently bound with the oxidized layer Theoxidized layer may be produced either on the finished article or on the raw material.

The oxidation of the surface may be effected b the use of alkali, hydrochloric acid, or meta lic chlorids in solution which latter to the present invention it is at the same time produce a colored deposit. Such metallic chloride may for instance be any of the chloride of ironor copper. The aluminum object or sheet is dipped in the solution of alkali, hydrochloric acid .or the like, or is brushed over with this solution, and the article is subsequently heated to red heat or incandescence, whereupon, if hydrochloric acid ora chlorid has been used, the chlorin is driven old leaving a hydrate of aluminum, which latter is reduced to the oxid, (alumina), on further heating.

In oxidation as above described, by means of metallic salts, such as the chloride of copper and iron, a colored deposit is produced which-may conveniently form the basis for the coloring of the metal; iron gives a gray coloration, copper a black A coating of enamel may now be applied.

Anilin compounds may be used as coloring agents which become colored by oxidation, or anilin colors may be used which will form compounds of alumina "with the oxid layer.

Having thus described my invention 1 declare what I claim is: a

- 1. The herein described method of treating the surface of aluminum which consists in coating the surface with an oxidizing agent and then subjecting the coated aluminum surface to the action of heat.

v 2. The herein described method of treating the surface of aluminum which consists in coating the surface with a metallic oxidizing salt and then subjecting the coated aluminum surface to the action of heat.

3. The hhrein described method of treating the surface'of aluminum which consists in coating the surface with a metallic chlorid and then subjecting the coated aluminum surface to the-action oi hea in witness whereof I have hereunto set my hand in presence of two witnesses.

. Y 4 ALBERT LANG.

Witnesses:

Srerninn Hansen, M. 'finn'rnm. 

